Leukemia is the most common cancer type in children, with approximately 5 cases per 100,000 children diagnosed annually in the United States. Between 20% and 30% of children with acute leukemia develop hyperleukocytosis, a condition characterized by an abnormally high white blood cell count, which can lead to life-threatening complications. While chemotherapy remains the primary treatment for acute leukemia, leukapheresis—an urgent procedure to reduce dangerously high white blood cell levels—can be a crucial, life-saving option. During leukapheresis, a machine uses centrifugation to separate white blood cells (leukocytes) from the rest of the blood, which is then returned to the patient. However, conventional blood-filtering machines pose risks to children due to issues such as high extracorporeal volume (ECV), high flow rates, and potential platelet loss. Now, new devices under development could improve the safety of this life-saving treatment for children with hyperleukocytosis.

A pioneering study led by researchers at the University of Houston (Houston, TX, USA), in collaboration with Baylor College of Medicine (Houston, TX, USA), examined whether a high-throughput microfluidic device could overcome the limitations of traditional blood-filtering machines in the treatment of children with hyperleukocytosis. This new microfluidic device features a series of tiny channels, roughly the width of a human hair, designed to separate blood cells efficiently by size through a process known as controlled incremental filtration.

During in vitro tests, the microfluidic devices successfully removed approximately 85% of large leukocytes and around 90% of leukemic blasts (abnormally proliferating cancerous white blood cells) from undiluted human whole blood. Leukemic blasts are immature white blood cells that do not develop correctly, proliferating too rapidly and crowding out normal blood cells. When tested in vivo, the device demonstrated similar efficiency in leukocyte collection without causing platelet loss or any adverse effects, while successfully recirculating undiluted whole blood for over three hours—approximately the typical duration of a leukapheresis procedure. These promising results, published in Nature Communications, highlight the potential of this microfluidic device to make leukapheresis safer and more effective for pediatric patients.

“Continuously and efficiently separating leukocytes from recirculating undiluted whole blood - without device clogging and cell activation or damage - has long been a major challenge in microfluidic cell separation. Our study is the first to solve this problem,” said Sergey Shevkoplyas, a professor of biomedical engineering at University of Houston. “Overall, our study suggests that microfluidics leukapheresis is safe and effective at selectively removing leukocytes from circulation, with separation performance sufficiently high to ultimately enable safe leukapheresis in children.”

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